This invention relates to the field of electro-optical integrated circuit die testing in the integral or whole wafer state of device fabrication.
Even though probe testing of integral wafer-contained circuit die for electrical properties has been a matter of routine accomplishment for years there remains some degree of difficulty in extending this test capability to electro-optical devices, devices which involve both electrical and optical or radiant energy signals as well as involving electrical signals. Devices of this nature may be referred to as signal transducer devices and generally include the charge coupled device or CCD family, the phototransistor, light responsive switching devices, and the photodiode, for examples. Testing of a combined electrical and optical nature may also be of value in evaluating the performance of some purely electrical signal-operated devices i.e., conventional transistor devices, which are subjected to unusual and light-inclusive operating conditions since photon-responsive characteristics are inherent in most transistors. The optical signal communication provided by the present invention is usable over a wide range of such devices and their test conditions.
The U.S. Patent art indicates the presence of considerable inventive activity relating to the fields of opto-electronic device and circuit die testing. The invention of Ravel et al, in U.S. Pat. No. 5,412,330 is for example of general interest with respect to such testing in the sense that it discloses use of a probe member, precise position control of test apparatus and optically communicated signals in the course of testing electro-optical material. The thrust of the Ravel et al. Invention appears however, to be in the area of substituting optical signals for electrical connection to a device-under-test.
Patents of background interest with respect to the present invention also include the patent of Alessi, U.S. Pat. No. 3,832,019, which is concerned with a three axis slide-inclusive micropositioning apparatus for testing integrated circuit devices. The thrust of the Alessi invention appears to be in the area of the mechanical slide apparatus.
Previous integrated circuit wafer testing patents also include the patent of Mallory, U.S. Pat. No. 4,755,746, a patent which is concerned with performance of sheet resistance measurements on a semiconductor wafer. The Mallory testing arrangement includes use of optical signals however, the invention appears not to be concerned with the probe testing of completed integrated circuit dice.
The previous integrated circuit testing patents also include a series of related patents assigned to Mostek Corporation of Carrolton Texas, patents which are concerned with the assembling and testing of integrated circuit devices. These patents include U.S. Pat. No. 4,722,060 and U.S. Pat. No. 4,685,998. The use of "a fiber-optic pigtail" to communicate optical signals between electrical devices located on a common integrated circuit wafer is indicated to be a possible "variation" of the disclosed apparatus in this series of patents.
The previous circuit testing patents also include the patent of Edmond et al., U.S. Pat. No. 5,381,103 which is concerned with accelerated degradation testing of a semiconductor device and with a combination optical and electrical measurement arrangement for measuring performance of the device-under-test. The Edmond apparatus in addition to this accelerated testing is primarily concerned with the application of large amplitude electrical signals to light emitting devices.